Add parser for FLAC metadata.

[sonitus.git] / src / main / java / net / pterodactylus / sonitus / io / flac / Data.java

diff --git a/src/main/java/net/pterodactylus/sonitus/io/flac/Data.java b/src/main/java/net/pterodactylus/sonitus/io/flac/Data.java
new file mode 100644 (file)
index 0000000..d054494
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/io/flac/Data.java
@@ -0,0 +1,114 @@
+/*
+ * Sonitus - Data.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sonitus.io.flac;
+
+import static com.google.common.io.ByteStreams.readFully;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * Accessor type that can parse the contents of a {@link MetadataBlock}.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class Data {
+
+       /** The content of the metadata block. */
+       private final byte[] content;
+
+       /**
+        * Creates a new data accessor.
+        *
+        * @param content
+        *              The content of the metadata block
+        */
+       public Data(byte[] content) {
+               this.content = content;
+       }
+
+       //
+       // ACCESSORS
+       //
+
+       /**
+        * Returns the content of this metadata block.
+        *
+        * @return The content of the metadata block
+        */
+       public byte[] content() {
+               return content;
+       }
+
+       //
+       // SUBCLASS METHODS
+       //
+
+       /**
+        * Parses the given number of bits from the content of this metadata block,
+        * starting at the given byte offset and bit offset (bit 0 being the most
+        * significant bit).
+        *
+        * @param byteOffset
+        *              The byte offset at which to start reading
+        * @param bitOffset
+        *              The bit offset at which to start reading
+        * @param numberOfBits
+        *              The number of bits to parse (should be <= 64)
+        * @return The parsed bits
+        */
+       protected long parseBits(int byteOffset, int bitOffset, int numberOfBits) {
+               long value = 0;
+               int currentByteOffset = byteOffset;
+               int currentBitOffset = bitOffset;
+               int bitsRemaining = numberOfBits;
+
+               while (bitsRemaining > 0) {
+                       value = (value << Math.min(8, bitsRemaining)) | ((content[currentByteOffset] & (0xff >>> currentBitOffset)) >> (8 - currentBitOffset - Math.min(bitsRemaining, 8 - currentBitOffset)));
+                       bitsRemaining -= Math.min(bitsRemaining, 8 - currentBitOffset);
+                       currentBitOffset = 0;
+                       currentByteOffset++;
+               }
+
+               return value;
+       }
+
+       //
+       // STATIC METHODS
+       //
+
+       /**
+        * Creates a new data accessor from the given input stream.
+        *
+        * @param inputStream
+        *              The input stream to read the contents of the metadata block from
+        * @param blockType
+        *              The type of the metadata block
+        * @param length
+        *              The length of the metadata block
+        * @return The parsed metadata block
+        * @throws IOException
+        *              if an I/O error occurs
+        */
+       public static Data parse(InputStream inputStream, BlockType blockType, int length) throws IOException {
+               byte[] buffer = new byte[length];
+               readFully(inputStream, buffer);
+               return blockType.createData(buffer);
+       }
+
+}